The sensory organ is the maxillary palp. It is one of three structures extending from the mosquito’s head that together provide it with its sense of smell and taste. The other two are the feathery antennae that serve as general-purpose olfactory organs and respond to a wide range of different chemicals and the proboscis that contains sensors designed for close-in odor and taste detection.
The detailed map of the maxillary palp, which was published online in the journal Current Biology on Aug. 30, has determined that it contains a unique array of highly specialized receptor cells that detect carbon dioxide and octenol, key chemical signals that the insects use to find human prey.
"These receptors are highly sensitive, which suggests that the maxillary palps may serve as the malaria mosquito’s long-range detection system,” says Tan Lu, a graduate student at Vanderbilt who is the paper’s first author.
“We haven’t proven it yet, but the implication is that if you took away the maxillary palp the mosquito would not do nearly as well at finding human prey,” adds Laurence J. Zwiebel, professor of biological sciences at Vanderbilt, who headed the study.
The research was performed by collaborators from Vanderbilt, Yale and Wageningen University in the Netherlands. They are part of a team that also includes researchers from the Ifakara Health Research and Development Centre in Tanzania and the Medical Research Council Laboratories in the Gambia that is funded by a grant from the Foundation for the National Institutes of Health through the Grand Challenges to Global Health Initiative in 2005 to develop a chemical strategy to combat the spread of malaria by the Anopheles mosquito.
“This paper marks a threshold in our grand challenge project because it provides a biological context and then strips it down to a few molecular targets that we are using to develop chemical modifiers that should have direct impacts on the mosquito’s behavior,” says Zwiebel.
The study fills a major gap in the scientific understanding of the malaria mosquito’s olfactory system. Although considerable research has been done on the physiology and molecular biology of Anopheles gambiae’s antennae and proboscis, there have been few studies of its maxillary palps. Most of the previous work that had been done on this “accessory olfactory appendage” was performed in another species of mosquito, Aedes aeqypti, the carrier of dengue and yellow fever.
Previous work found that the maxillary palps of the A. aeqypti were sensitive to carbon dioxide and octenol. So the discovery that this was also the case in An. gambiae did not come as a big surprise. However, the researchers found that the malaria mosquito uses different sets of receptors for this purpose which help explain why it appears to rely less on carbon dioxide and more on human-specific chemical compounds in seeking out hosts than does A. aegypti.
The mosquito’s elaborate “nose” consists of hundreds of hollow hair-like structures called sensilla attached to its antennae, maxillary palps and proboscis. The tips of these structures are perforated with thousands of tiny holes that let aromatic compounds penetrate to their interior, where they encounter thread-like extensions from neurons which are tuned to detect specific molecules.
Compared to the mosquito’s antennae, which are designed to detect hundreds of different compounds, the study found that the maxillary palps are highly specialized. “The amazing thing that we found was that all the sensory hairs that line the bottom of the maxillary palps are identical,” says Zwiebel. They are all attached to three neurons: one which is tuned to detect carbon dioxide; one which is tuned to detect octenol; and one which serves to enhance general olfactory reception.
In addition to Zwiebel and Lu, the Vanderbilt researchers who contributed to the study are Quirong Wang, Michael Rutzler, Hyung-Wook Kwon and R. Jason Pitts. The Wageningen team consists of Yu Tong Qiu, Joop J.A. van Loon and Willem Takken. The Yale contributors are Jae Young Kwon and John R. Carlson.
The research was funded by a Gates Foundation Grand Challenges in Global Health grant and by grants from the National Institutes of Health.
Vanderbilt University is a private research university of approximately 6,300 undergraduates and 4,600 graduate and professional students. Founded in 1873, the University comprises 10 schools, a public policy institute, a distinguished medical center and The Freedom Forum First Amendment Center. Vanderbilt, ranked as one of the nation’s top universities, offers undergraduate programs in the liberal arts and sciences, engineering, music, education and human development, and a full range of graduate and professional degrees.
David F. Salisbury | Vanderbilt University
New risk factors for anxiety disorders
24.02.2017 | Julius-Maximilians-Universität Würzburg
Stingless bees have their nests protected by soldiers
24.02.2017 | Johannes Gutenberg-Universität Mainz
In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport
Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...
The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.
The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...
Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...
Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".
Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...
13.02.2017 | Event News
10.02.2017 | Event News
09.02.2017 | Event News
24.02.2017 | Life Sciences
24.02.2017 | Life Sciences
24.02.2017 | Trade Fair News